SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81e533c58fd442e05855e6da465c6a51f5424a00996377fc9556054cecbf6351' 
  AND token = 'g7/tOH4GLqU6QqqGhTAG727629A1eMoWzYvOmPPjfC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}